Poly(vinyl butyral) (PVB) is commonly used in the manufacture of polymer sheets that can be used as interlayers in light-transmitting laminates such as safety glass or polymeric laminates. Safety glass often refers to a transparent laminate comprising a plasticized poly(vinyl butyral) sheet disposed between two sheets of glass. Safety glass often is used to provide a transparent barrier in architectural and automotive openings. Its main function is to absorb energy, such as that caused by a blow from an object, without allowing penetration through the opening or the dispersion of shards of glass, thus minimizing damage or injury to the objects or persons within an enclosed area. Safety glass also can be used to provide other beneficial effects, such as to attenuate acoustic noise, reduce UV and/or IR light transmission, and/or enhance the appearance and aesthetic appeal of window openings.
Interlayers that are particularly useful in applications in which the attenuation of noise is desired are often formulated to have a relatively low glass transition temperature. Because of the composition changes that are typically employed to attain a low glass transition temperature, however, interlayers can often have a tensile modulus that is less than desirable, making the interlayer either unsuitable or undesirable for use in some applications.
Among the various techniques that have been employed to overcome this problem is the modification of one or more of the components of the interlayer having a low glass transition temperature.
What are needed in the art are interlayers that are formulated to allow for easy handling of the interlayer while maintaining the sound attenuating qualities in multiple layer glazing applications in which noise suppression is desired and other applications.